Filed Pursuant to Rule 424(b)(5)
Registration No. 333-225320

PROSPECTUS SUPPLEMENT

(To Prospectus dated August 3, 2018)

$25,000,000

Common Stock

We have entered into an equity distribution agreement (the “Equity Distribution Agreement”) with Piper Jaffray & Co. (“Piper Jaffray”) as our sales agent, relating to shares of our common stock, par value $0.001 per share, offered by this prospectus supplement and the accompanying prospectus. In accordance with the terms of the Equity Distribution Agreement, we may offer and sell shares of our common stock having an aggregate offering price of up to $25.0 million from time to time through Piper Jaffray.

Our common stock trades on The Nasdaq Global Select Market (“Nasdaq”) under the symbol “ELGX.” On August 12, 2019, the last sale price of the common stock reported on Nasdaq was $6.45 per share.

Sales of our common stock, if any, under this prospectus supplement and the accompanying base prospectus may be made in sales deemed to be in negotiated transactions or transactions that are deemed “at the market offerings” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”) including sales made directly on Nasdaq or sales made to or through a market maker other than on an exchange. Piper Jaffray is not required to sell any specific number or dollar amount of our common stock, but will act as a sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between Piper Jaffray and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

The compensation to Piper Jaffray for sales of common stock sold pursuant to the Equity Distribution Agreement will be an amount of up to 3.0% of the gross proceeds of any shares of common stock sold thereunder. In connection with the sale of the common stock on our behalf, Piper Jaffray will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Piper Jaffray will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to Piper Jaffray with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended (the “Exchange Act”). The net proceeds we receive from any sales under this prospectus supplement will be used as described under “Use of Proceeds” in this prospectus supplement.

Investing in our common stock involves a high degree of risk. Please read “Risk Factors” beginning on page S- 8 of this prospectus supplement, on page 4 of the accompanying prospectus and in the documents incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission (the “SEC”), nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus, or determined if this prospectus supplement or accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Piper Jaffray

The date of this prospectus supplement is August 13, 2019.

TABLE OF CONTENTS

We have not, and Piper Jaffray has not, authorized anyone to provide any information or to make any representations other than those contained or incorporated by reference in this prospectus supplement or

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the accompanying prospectus. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus supplement and the accompanying prospectus together constitute an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. The information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus is current only as of its date. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein when making your investment decision. You should also read and consider the information in the documents we have referred you to in the section of the accompanying prospectus entitled “Incorporation of Certain Information by Reference.”

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ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus form part of a registration statement on Form S-3 that we filed with the SEC utilizing a “shelf” registration process. This document contains two parts. The first part consists of this prospectus supplement, which provides you with specific information about this offering. The second part, the accompanying prospectus, provides more general information, some of which may not apply to this offering. Generally, when we refer only to the “prospectus,” we are referring to both parts combined. This prospectus supplement may add, update or change information contained in the accompanying prospectus. To the extent that any statement we make in this prospectus supplement is inconsistent with statements made in the accompanying prospectus or any documents incorporated by reference herein or therein, the statements made in this prospectus supplement will be deemed to modify or supersede those made in the accompanying prospectus and such documents incorporated by reference herein and therein. You should read this prospectus supplement and the accompanying prospectus, including the information incorporated by reference herein and therein before deciding to invest in our common stock.

You should rely only on the information that we have included or incorporated by reference in this prospectus supplement and the accompanying prospectus. We have not, and Piper Jaffray has not, authorized any dealer, salesman or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus supplement or the accompanying prospectus. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus supplement or the accompanying prospectus. This prospectus supplement and the accompanying prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor does this prospectus supplement or the accompanying prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.

You should not assume that the information contained in this prospectus supplement or the accompanying prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference herein or therein is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus supplement or accompanying prospectus is delivered, or securities are sold, on a later date.

Unless otherwise mentioned or unless the context requires otherwise, all references in this prospectus supplement to the terms “Endologix,” “Company,” “we,” “our,” and “us” or similar references refer to Endologix, Inc. and our consolidated subsidiaries.

This prospectus supplement contains or incorporates by reference summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been or will be filed or have been or will be incorporated by reference as exhibits to the registration statement of which this prospectus supplement forms apart, and you may obtain copies of those documents as described in this prospectus supplement under the heading “Where You Can Find More Information.”

TRADEMARKS AND TRADE NAMES

We own or have rights to trademarks or trade names that we use in conjunction with the operation of our business. Each trademark, trade name or service mark of any other company appearing in this prospectus or any accompanying prospectus supplement belongs to its holder. Use or display by us of other parties’ trademarks, trade names or service marks is not intended to and does not imply a

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relationship with, or endorsement or sponsorship by us of, the trademark, trade name or service mark owner.

INDUSTRY AND MARKET DATA

We obtained the industry, market and competitive position data in this prospectus supplement from our own internal estimates and research as well as from industry and general publications and research surveys and studies conducted by third parties. While we believe that each of these studies and publications is reliable, we have not independently verified market and industry data from third-party sources. In addition, while we believe our internal company research is reliable and the market definitions we use are appropriate, neither our internal research nor these definitions have been verified by any independent source.

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein, contain forward-looking statements within the meaning of the federal securities laws. These forward-looking statements are intended to qualify for the safe harbor from liability established by the Private Securities Litigation Reform Act of 1995. All statements other than statements of historical fact included in this prospectus supplement, the accompanying prospectus or the documents incorporated by reference herein or therein, are forward looking statements.

Our forward-looking statements are based on our management’s current assumptions and expectations of future events and trends, which affect or may affect our business, strategy, operations or financial performance. Although we believe these forward-looking statements are based upon reasonable assumptions, they are subject to numerous known and unknown risks and uncertainties and are made in light of information currently available to us. Many important factors, in addition to the factors described in this prospectus supplement, may materially and adversely affect our results as indicated in our forward-looking statements. You should read this prospectus supplement, the accompanying prospectus and the documents we incorporate by reference herein and therein, completely and with the understanding that our actual future results may be materially different from and worse than what we expect.

Moreover, we operate in an evolving environment. New risk factors and uncertainties emerge from time to time and it is not possible for our management to predict all risk factors and uncertainties, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements. Actual results could differ materially from those projected in forward-looking statements as a result of the following factors, among others:

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Forward-looking statements speak only as of the date they were made, and, except to the extent required by law or the rules of Nasdaq, we undertake no obligation to update or review any forward-looking statement because of new information, future events or other factors. You should, however, review the risks and uncertainties we describe in the reports we will file from time to time with the SEC, after the date of this prospectus supplement. For more detailed information about the risks and uncertainties that could cause actual results to differ materially from those implied by, or anticipated in, these forward-looking statements, please refer to the section titled “Risk Factors” herein, as well as to the section titled “Risk Factors” in our Annual Report for the year ended December 31, 2018 on Form 10-K and subsequent updates that may be contained in our Quarterly Reports on Form 10-Q and current reports on Form 8-K on file with the SEC. See the information included under the heading “Where You Can Find More Information.”

Forward-looking statements involve risks and uncertainties and are not guarantees of future performance. As a result of the risks and uncertainties described above, the forward-looking statements discussed in this prospectus supplement might not occur and our future results and performance may differ materially from the information provided in these forward-looking statements due to, but not limited to, the factors mentioned above. Because of these uncertainties, you should not place undue reliance on these forward-looking statements when making an investment decision in us.

We qualify all of our forward-looking statements by these cautionary statements.

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SUMMARY

This summary highlights information contained or incorporated by reference in other parts of this prospectus supplement and the accompanying base prospectus. Because it is only a summary, it does not contain all of the information that you should consider before investing in shares of our common stock and it is qualified in its entirety by, and should be read in conjunction with, the more detailed information appearing elsewhere in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein and therein. You should read all such documents carefully, especially the risk factors and our financial statements and the related notes included or incorporated by reference herein or therein, before deciding to buy shares of our common stock. Unless the context requires otherwise, references in this prospectus to “Endologix,” the “Company,” “we,” “us” and “our” refer to Endologix, Inc. and our consolidated subsidiaries.

Our Business

We develop, manufacture, market and sell innovative medical devices for the treatment of aortic disorders. Our products are intended for the minimally invasive endovascular treatment of abdominal aortic aneurysms (“AAA”). Our AAA products are built on one of two platforms:

Our current EVAR products include the AFX ^® Endovascular AAA System (the “AFX System”), the VELA ^® Proximal Endograft (“VELA”) and the Ovation ^® Abdominal Stent Graft System (the “Ovation System”). Our current EVAS product is the Nellix ^® Endovascular Aneurysm Sealing System (the “Nellix EVAS System”). We sell our products through a direct sales force in the United States and internationally through a combination of direct sales and a network of third party distributors and agents.

Endologix ^® , AFX ^® , Duraply ^® , VELA ^® , IntuiTrak ^® , ActiveSeal ^® , Nellix ^® , Ovation ^® , Ovation Prime ^® , Ovation Alto ^® , and CustomSeal ^® are registered trademarks of Endologix, Inc. or its subsidiaries. The Ovation Alto ^® Abdominal Stent Graft System (the “Ovation Alto”), our next generation Ovation System device, is an investigational devices and is not currently approved for commercial purposes in any market. The Nellix Endovascular Aneurysm Sealing System (the “Nellix System”) has the CE Mark; it is an investigational device in the United States.

Market Overview and Opportunity

We estimate the global endovascular AAA market potential was $3.2 billion in 2018. Of this amount, we estimate the traditional aneurysm market potential, encompassing aneurysms with aortic neck length greater than or equal to 10mm, was approximately $1.8 billion. The majority of diagnosed aneurysms in this market can be treated with currently available EVAR products. We estimate that an approximately $1.4 billion market opportunity exists for the treatment of complex anatomies, defined as aneurysms with neck lengths less than 10mm. Currently, there are limited options among available EVAR products to treat these short or no neck aortic aneurysms.

Corporate Information

We were incorporated in California in March 1992 under the name Cardiovascular Dynamics, Inc. and reincorporated in Delaware in June 1993. In January 1999, we merged with Radiance Medical Systems, Inc. and changed our name to Radiance Medical Systems, Inc., which was a privately held corporation. In May 2002, we merged with Endologix, Inc., which was a privately held corporation, and changed our

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name to Endologix, Inc. Our main offices are located at 2 Musick, Irvine, California 92618, and our telephone number is (949) 595-7200. Additional information about Endologix, Inc. and our products is available through our website at www.endologix.com. The information contained on or accessed through our website is not incorporated by reference into this prospectus supplement, other than the documents that we file with the SEC that are expressly incorporated by reference into this prospectus supplement, and you should not consider information contained on our website to be a part of this prospectus supplement or in deciding whether to purchase our securities. References in this prospectus supplement to our website are to inactive textual references only.

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The Offering

The following is a brief summary of certain terms of this offering. For a more complete description of the terms of the common stock offered hereby, see the “Description of Capital Stock” section of the accompanying prospectus.

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RISK FACTORS

An investment in our common stock involves a high degree of risk. Before deciding whether to invest in our common stock, you should carefully consider the risks described below and those discussed under the Sections captioned “Risk Factors” contained in our Annual Report on Form 10-K for the year ended December 31, 2018, which is incorporated by reference in this prospectus supplement and the accompanying prospectus, together with other information in this prospectus supplement, the accompanying prospectus, and the information and documents incorporated by reference herein and therein. If any of these risks actually occurs, our business, financial condition, results of operations or cash flow could be seriously harmed. This could cause the trading price of our common stock to decline, resulting in a loss of all or part of your investment.

Risks Related to This Offering and Our Common Stock

Management will have broad discretion as to the use of the proceeds from this offering, and we may not use the proceeds effectively.

Because we have not designated the amount of net proceeds from this offering to be used for any particular purpose, our management will have broad discretion as to the application of the net proceeds from this offering and could use them for purposes other than those contemplated at the time of the offering. Our management may use the net proceeds for corporate purposes that may not improve our financial condition or market value.

You will experience immediate and substantial dilution in the net tangible book value per share of the common stock you purchase.

The shares sold in this offering, if any, will be sold from time to time at various prices. We expect that the offering price of our common stock will be substantially higher than the net tangible book value per share of our outstanding common stock. Our net tangible book value per share as of June 30, 2019 was $(7.13) and the last reported sale price of our common stock on Nasdaq on August 12, 2019 was $6.45 per share. After giving effect to the assumed sale of shares of our common stock in the aggregate amount of approximately $25.0 million at an assumed offering price of $6.45 per share, the last reported sale price of our common stock on August 12, 2019 on Nasdaq, and after deducting commissions and estimated offering expenses, our as adjusted net tangible book value as of June 30, 2019 would have been approximately $(99,355,793) million or approximately $(4.68) per share. This would represent an immediate increase in net tangible book value of approximately $2.45 per share to our existing stockholders and an immediate dilution in as adjusted net tangible book value of approximately $11.13 per share to purchasers of our common stock in this offering.

You may experience future dilution as a result of future equity offerings.

In order to raise additional capital, we may in the future offer additional shares of our common stock or other securities convertible into or exchangeable for our common stock at prices that may not be the same as the price per share in this offering. We may sell shares or other securities in any other offering at a price per share that is less than the price per share paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders. The price per share at which we sell additional shares of our common stock, or securities convertible or exchangeable into common stock, in future transactions may be higher or lower than the price per share paid by investors in this offering.

In addition, the sale of shares in this offering and any future sales of a substantial number of shares of our common stock in the public market, or the perception that such sales may occur, could adversely affect the price of our common stock. We cannot predict the effect, if any, that market sales of those shares of our common stock, or the perception that those shares may be sold, will have on the market price of our common stock.

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The market price for our common stock may be volatile and subject to future declines, and the value of an investment in our common stock may decline.

The price at which the shares of our common stock may be sold in the public market after they are purchased pursuant to this prospectus supplement may be lower than the price at which they are sold through or by Piper Jaffray. The market price of our shares of common stock may be volatile and be subject to wide fluctuations. Fluctuations in our stock price may be unrelated to or not otherwise reflect our historical financial performance and condition and prospects. The stock market in general can experience considerable price and volume fluctuations due to changes in general economic conditions or other factors beyond our control, which could impact the future market price of our shares of common stock. These broad market fluctuations may adversely affect the market price of our common stock. We cannot assure you that the market price of our shares of common stock will not be volatile or fluctuate or decline significantly in the future.

The sale of our common stock in this offering and any future sales of our common stock may depress our stock price and our ability to raise funds in new stock offerings.

Sales of our common stock in this offering and the public market following this offering could lower the market price of our common stock. Sales may also make it more difficult for us to sell equity securities or equity-related securities in the future at a time and price that our management deems acceptable, or at all.

Because we do not intend to declare cash dividends on our shares of common stock in the foreseeable future, stockholders must rely on appreciation of the value of our common stock for any return on their investment.

We have never declared or paid cash dividends on our common stock. We currently anticipate that we will retain future earnings for the development, operation and expansion of our business and do not anticipate declaring or paying any cash dividends in the foreseeable future. In addition, the terms of any existing or future debt agreements may preclude us from paying dividends. As a result, we expect that only appreciation of the price of our common stock, if any, will provide a return to investors in this offering for the foreseeable future.

If securities and/or industry analysts fail to continue publishing research about our business, if they change their recommendations adversely or if our results of operations do not meet their expectations, our stock price and trading volume could decline.

The trading market for our common stock will be influenced by the research and reports that industry or securities analysts publish about us or our business. If one or more of these analysts cease coverage of our company or fail to publish reports on us regularly, we could lose visibility in the financial markets, which in turn could cause our stock price or trading volume to decline. In addition, it is likely that in some future period our operating results will be below the expectations of securities analysts or investors. If one or more of the analysts who cover us downgrade our stock, or if our results of operations do not meet their expectations, our stock price could decline.

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USE OF PROCEEDS

We may issue and sell shares of our common stock having aggregate gross proceeds of up to $25,000,000 from time to time under this prospectus supplement and accompanying base prospectus. Because there is no minimum offering amount required as a condition to close this offering, the actual total offering amount, commissions and proceeds to us, if any, are not determinable at this time. The amount of proceeds from this offering will depend upon the number of shares of our common stock sold and the market price at which they are sold. There can be no assurance that we will be able to sell any shares under or fully utilize the Equity Distribution Agreement with Piper Jaffray as a source of financing.

We intend to use the net proceeds from this offering for general corporate purposes, including manufacturing expenses, clinical trial expenses, research and development expenses, sales and marketing expenses, general and administrative expenses. We may also use a portion of the net proceeds to acquire or invest in complementary businesses, products and technologies. Although we have no specific agreements, commitments or understandings with respect to any acquisition, we evaluate acquisition opportunities and engage in related discussions with other companies from time to time. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses of the proceeds, if any, from this offering. Accordingly, we will retain broad discretion over the use of any such proceeds. Pending the use of the net proceeds, from this offering as described above, we intend to invest the net proceeds in investment-grade, interest-bearing instruments.

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DILUTION

As of June 30, 2019, our net tangible book value was $(123.7) million, or $(7.13) per share. Net tangible book value per share represents our total tangible assets less our total liabilities, divided by the number of shares outstanding.

For illustrative purposes only, we assume that we will issue and sell an aggregate of 3,875,969 shares of our common stock during the term of the Equity Distribution Agreement with Piper Jaffray at a price of $6.45 per share, the last reported sale price of our common stock on Nasdaq on August 12, 2019, for aggregate gross proceeds of approximately $25.0 million. The shares subject to the Equity Distribution Agreement with Piper Jaffray are being sold from time to time at various prices.

After giving effect to the assumed issuance and sale by us 3,875,969 shares of our common stock in this offering at an assumed offering price of $6.45 per share, and after deducting estimated offering expenses payable by us, our as adjusted net tangible book value as of June 30, 2019 would have been $(99,355,793 million, or $(4.68) per share.

This amount represents an immediate increase in net tangible book value of $2.45 per share to our existing stockholders and immediate dilution in net tangible book value of $11.13 per share to new investors purchasing shares in this offering. We determine dilution by subtracting the as adjusted net tangible book value per share after this offering from the assumed price per share paid by an investor in this offering.

The following table illustrates this dilution.

An increase of $0.50 per share in the price at which the shares are sold from the assumed offering price of $6.45 per share shown in the table above, assuming all of our common stock in the aggregate amount of approximately $25.0 million during the term of the Equity Distribution Agreement with Piper Jaffray is sold at that price, would decrease our adjusted net tangible book value per share after the offering to $(4.74) per share and would increase the dilution in net tangible book value per share to new investors in this offering to $11.69 per share, after deducting commissions and estimated aggregate offering expenses payable by us. A decrease of $0.50 per share in the price at which the shares are sold from the assumed offering price of $6.45 per share shown in the table above, assuming all of our common stock in the aggregate amount of approximately $25.0 million during the term of the Equity Distribution Agreement with Piper Jaffray is sold at that price, would increase our adjusted net tangible book value per share after the offering to $(4.61) per share and would decrease the dilution in net tangible book value per share to new investors in this offering to $10.56 per share, after deducting commissions and estimated offering expenses payable by us. This information is supplied for illustrative purposes only and may differ based on the actual offering price and the actual number of shares offered.

The number of shares of our common stock to be outstanding after this offering is based on 17,352,698 shares of our common stock outstanding as of June 30, 2019 and excludes:

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Our option holders and warrant holders may exercise the above-referenced options and warrants in the future or we may make future grants under the above-referenced plans. In addition, we may choose to raise additional capital through the sale of equity or convertible debt securities due to market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans. To the extent that any of these options or warrants are exercised, new options or shares of our common stock are issued under the above-referenced plans, or we issue additional shares of our common stock or other equity securities in the future, there will be further dilution to investors purchasing in this offering.

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MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES TO NON-U.S. HOLDERS

The following is a general discussion of the material U.S. federal income tax consequences of the acquisition, ownership and disposition of our common stock by “Non-U.S. Holders” (as defined below). This discussion is a summary for general information purposes only and does not consider all aspects of U.S. federal income taxation that may be relevant to particular Non-U.S. Holders in light of their individual circumstances or to certain types of Non-U.S. Holders subject to special tax rules under the Internal Revenue Code of 1986, as amended, or the Code, including partnerships or other pass-through entities for U.S. federal income tax purposes (or investors in such entities), banks, financial institutions or other financial services entities, broker-dealers, insurance companies, tax-exempt organizations, regulated investment companies, real estate investment trusts, controlled foreign corporations, passive foreign investment companies, corporations that accumulate earnings to avoid U.S. federal income tax, persons who use or are required to use mark-to-market accounting, persons that hold our shares of common stock as part of a “straddle,” a “hedge” or a “conversion transaction,” persons for whom our stock constitutes “qualified small business stock” within the meaning of Section 1202 of the Code, certain former citizens or permanent residents of the U.S., “qualified foreign pension funds” as defined in Section 897(l)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds or persons subject to special tax accounting rules as a result of any item of gross income with respect to the stock being taken into account in an applicable financial statement. In addition, this summary does not address the effects of any applicable gift or estate tax, and this summary does not address the potential application of the alternative minimum tax, Medicare contribution tax or any tax considerations that may apply to Non-U.S. Holders of our common stock under state, local or non-U.S. tax laws or any other U.S. federal tax laws.

This summary is based on the Code, and applicable Treasury Regulations, rulings, administrative pronouncements and decisions as of the date of this prospectus supplement, all of which are subject to change or differing interpretations at any time with possible retroactive effect. We have not sought, and will not seek, any ruling from the Internal Revenue Service, or the IRS, with respect to the tax consequences discussed herein, and there can be no assurance that the IRS will not take a position contrary to the tax consequences discussed below or that any position taken by the IRS would not be sustained. This discussion assumes that a Non-U.S. Holder will hold our common stock as a “capital asset” within the meaning of Section 1221 of the Code (generally, property held for investment).

The following discussion is for general information only and is not tax advice for any Non-U.S. Holder under its particular circumstances. Persons considering the purchase of our common stock pursuant to this offering should consult their tax advisors concerning the U.S. federal income, estate and gift tax consequences of acquiring, owning and disposing of our common stock in light of their particular situations as well as any consequences arising under the laws of any other taxing jurisdiction, including any state, local and non-U.S. tax consequences and the possible application of tax treaties that might change the general provisions discussed below.

For purposes of this discussion, the term “Non-U.S. Holder” means a beneficial owner of our shares of common stock that is not a partnership (or entity or arrangement treated as a partnership for U.S. federal income tax purposes) or an entity that is treated as a disregarded entity for U.S. federal income tax purposes and is not:

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If a partnership (or entity or arrangement treated as a partnership for U.S. federal income tax purposes) or an entity that is treated as a disregarded entity for U.S. federal income tax purposes (regardless of its place of organization or formation) holds our common stock, the tax treatment of a partner in the partnership or the owner of the disregarded entity will generally depend upon the status of the partner or the owner of the disregarded entity and the activities of the partnership or the disregarded entity. If you are a partner of a partnership holding our common stock or the owner of a disregarded entity holding our common stock, you should consult your tax advisor regarding the tax consequences of the purchase, ownership, and disposition of our common stock.

PROSPECTIVE INVESTORS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE PARTICULAR U.S. FEDERAL INCOME TAX CONSEQUENCES TO THEM OF ACQUIRING, OWNING AND DISPOSING OF OUR COMMON STOCK, AS WELL AS ANY TAX CONSEQUENCES ARISING UNDER ANY STATE, LOCAL OR FOREIGN TAX LAWS AND ANY OTHER U.S. FEDERAL TAX LAWS.

Distributions on Our Common Stock

In general, distributions, if any, paid to a Non-U.S. Holder (to the extent paid out of our current or accumulated earnings and profits, as determined under U.S. federal income tax principles) will constitute dividends and be subject to U.S. withholding tax at a rate equal to 30% of the gross amount of the dividend, or a lower rate prescribed by an applicable income tax treaty, unless the dividends are effectively connected with a trade or business carried on by the Non-U.S. Holder within the United States. Any distribution not constituting a dividend (because such distribution exceeds our current and accumulated earnings and profits) will be treated first as reducing the Non-U.S. Holder’s basis in its shares of common stock, but not below zero, and to the extent it exceeds the Non-U.S. Holder’s basis, as capital gain and will be treated as described below under “Gain on Sale, Exchange or Other Disposition of Our Common Stock”.

A Non-U.S. Holder who claims the benefit of an applicable income tax treaty with respect to withholding on dividends paid on our common stock generally will be required to satisfy certain certification and other requirements prior to the distribution date. Non-U.S. Holders must generally provide the withholding agent with a properly executed IRS Form W-8BEN, Form W-8BEN-E or other appropriate form claiming an exemption from or reduction in withholding under an applicable income tax treaty. This certification must be updated periodically. If a Non-U.S. Holder holds our common stock through a financial institution or other agent acting on the Non-U.S. Holder’s behalf, the Non-U.S. Holder will be required to provide appropriate documentation to the agent, who then will be required to provide certification to us or our paying agent, either directly or through other intermediaries. If tax is withheld in an amount in excess of the amount applicable under an income tax treaty, a refund of the excess amount may generally be obtained by timely filing an appropriate claim for refund with the IRS. Non-U.S. Holders should consult their tax advisors regarding their entitlement to benefits under an applicable income tax treaty.

Dividends that are effectively connected with a Non-U.S. Holder’s conduct of a U.S. trade or business (and, if required by an applicable income tax treaty, attributable to a U.S. permanent establishment or fixed base of the Non-U.S. Holder) generally will not be subject to U.S. withholding tax if the Non-U.S. Holder provides the withholding agent with the required forms, including IRS Form W-8ECI, but instead

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generally will be subject to U.S. federal income tax on a net income basis at the regular graduated rates in the same manner as if the Non-U.S. Holder were a resident of the United States. A corporate Non-U.S. Holder that receives effectively connected dividends may also be subject to an additional branch profits tax at a rate of 30% (or a lower rate prescribed by an applicable income tax treaty) of its effectively connected earnings and profits for the taxable year, as adjusted for certain items.

Gain on Sale, Exchange or Other Disposition of Our Common Stock

In general, a Non-U.S. holder will not be subject to any U.S. federal income tax or withholding tax on any gain realized upon such holder’s sale, exchange or other disposition of shares of our common stock unless:

Net gain realized by a Non-U.S. Holder described in the first bullet point above generally will be subject to U.S. federal income tax in the same manner as if the Non-U.S. Holder were a resident of the United States. Any gains of a corporate Non-U.S. Holder described in the first bullet point above may also be subject to an additional branch profits tax at a 30% rate, or such lower rate as may be specified by an applicable income tax treaty.

Gain realized by an individual Non-U.S. Holder described in the second bullet point above will be subject to a flat 30% (or such lower rate specified by an applicable income tax treaty) tax, which gain may be offset by certain U.S. source capital losses, even though the individual is not considered a resident of the United States, provided that the Non-U.S. Holder has timely filed U.S. federal income tax returns with respect to such losses.

For purposes of the third bullet point above, a corporation is a “United States real property holding corporation” if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. We believe that we are not, and we do not anticipate that we will become, a United States real property holding corporation. However, because the determination of whether we are a United States real property holding corporation depends on the fair market value of our U.S. real property interests relative to the fair market value of our other business assets, there can be no assurance that we will not become a United States real property holding corporation in the future. If we become a United States real property holding corporation, as long as our common stock is regularly traded on an established securities market, our common stock will be treated as a U.S. real property interest only with respect to a Non-U.S. Holder that actually or constructively held more than 5% of our common stock at any time during the shorter of the two periods described in the third bullet point above. If gain on the sale or other taxable disposition of our common stock were subject to taxation under the third bullet point above, the Non-U.S. Holder would be subject to U.S. federal income tax with respect to such gain in the same manner a Non-U.S. Holder described in the first bullet point above.

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Information Reporting and Backup Withholding

Generally, we must report annually to the IRS and to each Non-U.S. Holder the amount of dividends paid, the name and address of the recipient, and the amount, if any, of tax withheld. These information reporting requirements apply even if withholding was not required because the dividends were effectively connected with the Non-U.S. Holder’s conduct of a trade or business within the U.S. or withholding was reduced by an applicable income tax treaty. Under applicable income tax treaties or other agreements, the IRS may make its reports available to the tax authorities in the Non-U.S. Holder’s country of residence.

Dividends paid to a Non-U.S. Holder that is not an exempt recipient generally will be subject to backup withholding, currently at a rate of 24%, unless the Non-U.S. Holder certifies to the withholding agent as to its foreign status, which certification may generally be made on IRS Form W-8BEN, Form W-8BEN-E or other appropriate version of IRS Form W-8. Notwithstanding the foregoing, backup withholding may apply if either we or our paying agent has actual knowledge, or reason to know, that the holder is a United States person that is not an exempt recipient.

Proceeds from the sale or other disposition of common stock by a Non-U.S. Holder effected by or through a U.S. office of a broker will generally be subject to information reporting and backup withholding, currently at a rate of 24%, unless the Non-U.S. Holder certifies to the withholding agent under penalties of perjury as to, among other things, its name, address and non-U.S. status or otherwise establishes an exemption. Payment of disposition proceeds effected outside the United States by or through a non-U.S. office of a non-U.S. broker generally will not be subject to information reporting or backup withholding if the payment is not received in the United States. Information reporting, but generally not backup withholding (provided the broker does not have actual knowledge or reason to know that the holder is a United States person that is not an exempt recipient), will apply to such a payment if the broker has certain connections with the United States unless the broker has documentary evidence in its records that the beneficial owner thereof is a Non-U.S. Holder and specified conditions are met or an exemption is otherwise established.

Backup withholding is not an additional tax. Any amount withheld under the backup withholding rules from a payment to a Non-U.S. Holder that results in an overpayment of taxes generally will be refunded, or credited against the holder’s U.S. federal income tax liability, if any, provided that the required information is timely furnished to the IRS.

Additional Withholding Tax on Payments Made to Foreign Accounts

Withholding taxes may be imposed under Sections 1471 to 1474 of the Code (such Sections commonly referred to as the Foreign Account Tax Compliance Act, or “FATCA”) on certain types of payments made to non-U.S. financial institutions and certain other non-U.S. entities. Specifically, a 30% withholding tax may be imposed on dividends on, or gross proceeds from the sale or other disposition of, our common stock paid to a “foreign financial institution” or a “non-financial foreign entity” (each as defined in the Code), unless (1) the foreign financial institution undertakes certain diligence and reporting obligations, (2) the non-financial foreign entity either certifies it does not have any “substantial United States owners” (as defined in the Code) or furnishes identifying information regarding each substantial United States owner, or (3) the foreign financial institution or non-financial foreign entity otherwise qualifies for an exemption from these rules. If the payee is a foreign financial institution and is subject to the diligence and reporting requirements in (1) above, it must enter into an agreement with the U.S. Department of the Treasury requiring, among other things, that it undertake to identify accounts held by certain “specified United States persons” or “United States owned foreign entities” (each as defined in the Code), annually report certain information about such accounts, and withhold 30% on certain payments to non-compliant foreign financial institutions and certain other account holders. Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing FATCA may be subject to different rules.

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Under the applicable Treasury Regulations and administrative guidance, withholding under FATCA generally applies to payments of dividends on our common stock. While withholding under FATCA would have also applied to payments of gross proceeds from the sale or other disposition of such stock on or after January 1, 2019, recently proposed Treasury Regulations eliminate FATCA withholding on payments of gross proceeds entirely. Taxpayers generally may rely on these proposed Treasury Regulations until final Treasury Regulations are issued.

Prospective investors should consult their tax advisors regarding the potential application of withholding under FATCA to their investment in our common stock.

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PLAN OF DISTRIBUTION

We have entered into an Equity Distribution Agreement with Piper Jaffray as our sales agent under which we may offer and sell shares of our common stock having an aggregate gross offering price of up to $25,000,000 from time to time. Piper Jaffray will use commercially reasonable efforts to sell on our behalf all of the shares of our common stock requested to be sold by us, consistent with its normal trading and sales practices, under the terms and subject to the conditions set forth in the Equity Distribution Agreement. We may instruct Piper Jaffray not to sell our common stock if the sales cannot be effected at or above the price designated by us in any instruction. We or Piper Jaffray may suspend the offering of our common stock upon proper notice and subject to other conditions, as further described in the Equity Distribution Agreement. A copy of the Equity Distribution Agreement has been filed as an exhibit to a Current Report on Form 8-K and is incorporated by reference into the registration statement of which this prospectus supplement is a part.

Piper Jaffray will provide written confirmation to us following the close of trading on Nasdaq each day in which our common stock is sold under the Equity Distribution Agreement. Each such confirmation will include the number of shares of common stock sold on such day, the net proceeds to us and the compensation payable by us to Piper Jaffray in connection with the sales of common stock.

We will pay Piper Jaffray commissions for its services in acting as agent and/or principal in the sale of common stock. Piper Jaffray will be entitled to compensation in an amount up to 3.0% of the gross sales price of all common stock sold through it as agent under the Equity Distribution Agreement. However, in the event Piper Jaffray acts as principal in the sale of common stock under the Equity Distribution Agreement, such rate of compensation will not apply, but in no event will the total compensation of Piper Jaffray, when combined with the reimbursement of Piper Jaffray for the out-of-pocket fees and disbursements of its legal counsel as described below, exceed 8.0% of the gross proceeds received from the sale of the common stock. We estimate that the total expenses for the offering, excluding compensation payable to Piper Jaffray under the terms of the Equity Distribution Agreement, will be approximately $185,000. We have also agreed to reimburse Piper Jaffray for the out-of-pocket reasonable fees and disbursements of its legal counsel, in an amount not to exceed $50,000.

Settlement for sales of common stock will occur on the second business day following the date on which any sales are made, or on some other date that is agreed upon by us and Piper Jaffray in connection with a particular transaction, in return for payment of the net proceeds to us. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will report at least quarterly the number of shares of common stock sold through Piper Jaffray, as sales agent, under the Equity Distribution Agreement, the net proceeds to us and the compensation paid by us to Piper Jaffray in connection with the sales of common stock.

Piper Jaffray and its affiliates have provided, and may in the future provide, various investment banking, commercial banking, fiduciary and advisory services for us from time to time for which they have received, and may in the future receive, customary fees and expenses. Piper Jaffray and its affiliates may, from time to time, engage in other transactions with and perform services for us in the ordinary course of their business.

In connection with the sale of the common stock on our behalf, Piper Jaffray may, and will with respect to sales effected in an “at-the-market” equity offering, be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Piper Jaffray may be deemed to be underwriting commissions or discounts. We have agreed to indemnify Piper Jaffray against specified liabilities, including liabilities under the Securities Act, or to contribute to payments that Piper Jaffray may be required to make because of those liabilities.

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The offering of shares of our common stock pursuant to the Equity Distribution Agreement will terminate upon the earlier of (1) the sale of all common stock subject to the Equity Distribution Agreement or (2) termination of the Equity Distribution Agreement. The Equity Distribution Agreement may be terminated by Piper Jaffray or us at any time on the close of business on the date of receipt of written notice, and by Piper Jaffray at any time in certain circumstances, including any suspension or limitation on the trading of our common stock on Nasdaq, as further described in the Equity Distribution Agreement.

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LEGAL MATTERS

The validity of the securities being offered by this prospectus supplement will be passed upon for us by DLA Piper LLP (US), San Diego, California. Certain attorneys affiliated with DLA Piper LLP (US) collectively own an aggregate of 15,128 shares of our common stock. Piper Jaffray is being represented in connection with this offering by Latham & Watkins LLP, Chicago, Illinois.

EXPERTS

The consolidated financial statements and schedule of Endologix, Inc. as of December 31, 2018 and 2017 and for each of the years in the three-year period ended December 31, 2018, and management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2018, have been incorporated by reference herein in reliance upon the reports of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

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WHERE YOU CAN FIND MORE INFORMATION

This prospectus supplement and the accompanying prospectus form part of a registration statement on Form S-3 that we filed with the SEC. This prospectus supplement and the accompanying prospectus do not contain all of the information set forth in the registration statement and the exhibits to the registration statement or the documents incorporated by reference herein and therein. For further information with respect to us and the securities that we are offering under this prospectus supplement, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement and the documents incorporated by reference herein and therein. You should rely only on the information contained in this prospectus supplement or the accompanying prospectus or incorporated by reference herein or therein. We have not authorized anyone else to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus supplement is accurate as of any date other than the date on the front page of this prospectus supplement, regardless of the time of delivery of this prospectus supplement or any sale of the securities offered hereby.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC, including Endologix, Inc. The address of the SEC website is www.sec.gov.

We maintain a website at www.endologix.com. Information contained in or accessible through our website does not constitute a part of this prospectus supplement.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate” into this prospectus supplement information that we file with the SEC in other documents. This means that we can disclose important information to you by referring to other documents that contain that information. Any information that we incorporate by reference into this prospectus supplement is considered part of this prospectus supplement.

Information contained in this prospectus supplement and information that we file with the SEC in the future and incorporate by reference in this prospectus supplement automatically modifies and supersedes previously filed information, including information in previously filed documents or reports that have been incorporated by reference in this prospectus supplement, to the extent the new information differs from or is inconsistent with the old information. Any statement so modified will be deemed to constitute a part of this prospectus supplement only as so modified, and any statement so superseded will be deemed not to constitute a part of this prospectus supplement.

We incorporate by reference, as of their respective dates of filing, the documents listed below that we have filed with the SEC and any future documents that we file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including any documents filed after the date of the initial registration statement of which this prospectus supplement is a part until the offering of the securities covered by this prospectus supplement has been completed, other than, in each case, documents or information deemed to have been “furnished” and not “filed” in accordance with SEC rules:

These filings have not been included in or delivered with this prospectus supplement. We will provide to each person, including any beneficial owner to whom this prospectus supplement is delivered, a copy of any document that is incorporated by reference in this prospectus supplement. You may obtain a copy of these documents, at no cost, from our website (www.endologix.com) or by contacting us using the following information:

Endologix, Inc.

2 Musick

Irvine, California 92618

Attention: Investor Relations

(949) 595-7200

Exhibits to the documents will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus supplement.

S-22

$100,000,000

ENDOLOGIX, INC.

Common Stock

Preferred Stock

Warrants

Units

We may offer and sell, from time to time in one or more offerings, any combination of common stock, preferred stock, warrants and/or units having an aggregate initial offering price not to exceed $100,000,000. The preferred stock may be convertible into or exchangeable for other shares of our preferred stock, shares of our common stock or warrants. The warrants may be exercisable for shares of our common stock, shares of our preferred stock, and/or units.

This prospectus provides a general description of the securities we may offer. Each time we sell a particular class of securities, we will provide specific terms of the securities offered in a supplement to this prospectus. The prospectus supplement may also add, update or change information in this prospectus. You should read this prospectus and any prospectus supplement, as well as the documents incorporated by reference or deemed to be incorporated by reference herein or therein, carefully before you invest in any of the securities offered pursuant to this prospectus.

This prospectus may not be used to offer or sell our securities unless accompanied by a prospectus supplement relating to the offered securities.

These securities may be sold directly by us, through dealers or agents designated from time to time, to or through underwriters or dealers or through a combination of these methods on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus. We will describe the plan of distribution for any particular offering of our securities in a prospectus supplement. If any agents, underwriters or dealers are involved in the sale of any securities with respect to which this prospectus is being delivered, we will set forth in a prospectus supplement the names of such agents or underwriters and any applicable fees, commissions, discounts and over-allotment options. We will also set forth in a prospectus supplement the price to the public of such securities and the net proceeds we expect to receive from such sale.

Our common stock is listed on the NASDAQ Global Select Market and traded under the symbol “ELGX.” On May 30, 2018, the last reported sale price for our common stock on the NASDAQ Global Select Market was $5.64 per share.

INVESTING IN OUR SECURITIES INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD REVIEW CAREFULLY THE RISKS AND UNCERTAINTIES DESCRIBED UNDER THE HEADING “ RISK FACTORS ” BEGINNING ON PAGE 4 OF THIS PROSPECTUS, AS WELL AS THE RISKS AND UNCERTAINTIES DESCRIBED UNDER A SIMILAR HEADING IN ANY APPLICABLE PROSPECTUS SUPPLEMENT AND IN THE DOCUMENTS THAT WE INCORPORATE BY REFERENCE HEREIN OR THEREIN.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is August 3, 2018

TABLE OF CONTENTS

PROSPECTUS

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or the SEC, using a “shelf” registration process. Under this shelf registration process, we may from time to time offer and sell any combination of the securities described in this prospectus in one or more offerings with an aggregate initial offering price not to exceed $100,000,000. We have provided to you in this prospectus a general description of the securities we may offer. Each time we offer or sell any of our securities under this prospectus, we will, to the extent required by law, provide a prospectus supplement that will contain specific information about the terms of the offering.

We may add, update or change any of the information contained in this prospectus or in any accompanying prospectus supplement we may authorize to be delivered to you. To the extent there is a conflict between the information contained in this prospectus and any accompanying prospectus supplement, you should rely on the information in the prospectus supplement, provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in this prospectus or any prospectus supplement—the statement in the document having the later date modifies or supersedes the earlier statement. Any statement so modified will be deemed to constitute a part of this prospectus only as so modified, and any statement so superseded will be deemed not to constitute a part of this prospectus. This prospectus, together with any accompanying prospectus supplement, includes all material information relating to an offering pursuant to this registration statement.

You should rely only on the information contained in this prospectus, in any accompanying prospectus supplement, or in any document incorporated by reference herein or therein. We have not authorized anyone to provide you with any different information. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may provide to you. The information contained in this prospectus, in any applicable prospectus supplement, and in the documents incorporated by reference herein or therein is accurate only as of the date such information is presented. Our business, financial condition, results of operations and future prospects may have changed since those respective dates.

This prospectus and any accompanying prospectus supplement does not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor does this prospectus and any accompanying prospectus supplement constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. This prospectus may not be used to offer or sell our securities unless accompanied by a prospectus supplement relating to the offered securities.

The registration statement containing this prospectus, including the exhibits to the registration statement, provides additional information about us and the securities offered pursuant to this prospectus. For a more complete understanding of the offering of the securities, you should refer to the registration statement, including its exhibits. The registration statement can be read on the SEC’s website or at the SEC’s offices mentioned under the heading “Where You Can Find More Information.”

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SPECIAL NOTE REGARDING FORWARD-LOOKING INFORMATION

This prospectus, any accompanying prospectus supplement, and the documents incorporated by reference herein and therein, contain forward-looking statements within the meaning of the federal securities laws. These forward-looking statements are intended to qualify for the safe harbor from liability established by the Private Securities Litigation Reform Act of 1995. All statements other than statements of historical fact included in this prospectus, any accompanying prospectus supplement, or the documents incorporated by reference herein or therein, are forward looking statements.

Our forward-looking statements are based on our management’s current assumptions and expectations of future events and trends, which affect or may affect our business, strategy, operations or financial performance. Although we believe these forward-looking statements are based upon reasonable assumptions, they are subject to numerous known and unknown risks and uncertainties and are made in light of information currently available to us. Many important factors, in addition to the factors described in this prospectus, may materially and adversely affect our results as indicated in our forward-looking statements. You should read this prospectus, any accompanying prospectus supplement, and the documents we incorporate by reference herein and therein, completely and with the understanding that our actual future results may be materially different from and worse than what we expect.

Moreover, we operate in an evolving environment. New risk factors and uncertainties emerge from time to time and it is not possible for our management to predict all risk factors and uncertainties, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements.

Forward-looking statements speak only as of the date they were made, and, except to the extent required by law or the rules of the NASDAQ Stock Market, we undertake no obligation to update or review any forward-looking statement because of new information, future events or other factors. You should, however, review the risks and uncertainties we describe in the reports we will file from time to time with the SEC, after the date of this prospectus. See the information included under the heading “Where You Can Find More Information.”

Forward-looking statements involve risks and uncertainties and are not guarantees of future performance. As a result of the risks and uncertainties described above, the forward-looking statements discussed in this prospectus might not occur and our future results and performance may differ materially from the information provided in these forward-looking statements due to, but not limited to, the factors mentioned above. Because of these uncertainties, you should not place undue reliance on these forward-looking statements when making an investment decision.

We qualify all of our forward-looking statements by these cautionary statements.

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ABOUT THE COMPANY

Overview

We develop, manufacture, market, and sell innovative medical devices for the treatment of aortic disorders. Our products are intended for the minimally invasive endovascular treatment of abdominal aortic aneurysms (“AAA”). Our AAA products are built on one of two platforms:

Our current EVAR products include the AFX ^® Endovascular AAA System (the “AFX System”), the VELA ^® Proximal Endograft (“VELA”), and the Ovation ^® Abdominal Stent Graft System (the “Ovation System”). Our current EVAS product is the Nellix ^® Endovascular Aneurysm Sealing System (the “Nellix EVAS System”). We sell our EVAR platforms (including extensions and accessories) to hospitals in the United States, Canada, New Zealand, South Korea and Europe, and our EVAS platform to hospitals in New Zealand and Europe. We sell our EVAR and EVAS platforms (including extensions and accessories) to third-party international distributors and agents in Asia, Europe, South America and in other parts of the world. Such sales of our EVAR and EVAS platforms provide the sole source of our reported revenue.

Endologix ^® , AFX ^® , Duraply ^® , VELA ^® , IntuiTrak ^® , ActiveSeal ^® , Nellix ^® , Ovation ^® , Ovation Prime ^® , Ovation Alto ^® , and CustomSeal ^® are registered trademarks of Endologix, Inc. and its subsidiaries.

We have obtained CE Mark approval for the Nellix EVAS System in the European Union. The Nellix EVAS System is only approved as an investigational device in the United States. Ovation Alto, our next generation Ovation System device, is only approved as an investigational device and is not currently approved in any market.

Corporate Information

We were incorporated in California in March 1992 under the name Cardiovascular Dynamics, Inc. and reincorporated in Delaware in June 1993. In January 1999, we merged with Radiance Medical Systems, Inc. and changed our name to Radiance Medical Systems, Inc., which was a privately-held corporation. In May 2002, we merged with Endologix, Inc., which was a privately held corporation, and changed our name to Endologix, Inc. Our main offices are located at 2 Musick, Irvine, California 92618, and our telephone number is (949) 595-7200. Additional information about Endologix, Inc. and our products is available through our website at www.endologix.com. The information contained on or accessed through our website is not incorporated by reference into this prospectus, and you should not consider information contained on our website to be a part of this prospectus or in deciding whether to purchase our securities. References in this prospectus to our website are to inactive textual references only.

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RISK FACTORS

Investing in our securities involves a high degree of risk. Before making an investment decision, you should carefully consider the risks described in the sections entitled “Risk Factors” in our most recent Annual Report on Form 10-K and subsequent Quarterly Reports on Form 10-Q, as filed with the SEC, which are incorporated by reference in this prospectus in their entirety, as well as any amendments or updates to our risk factors reflected in subsequent filings with the SEC, including any applicable prospectus supplement. If any of these risks actually occur, our business, financial condition, results of operations and future prospects could be materially and adversely affected. In that case, the trading price of our securities could decline and you might lose all or part of your investment. For more information, see “Where You Can Find More Information.”

The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our business, financial condition or results of operations.

This prospectus and the documents we incorporate by reference in this prospectus contain forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks and uncertainties mentioned elsewhere in this prospectus. For more information, see “Special Note Regarding Forward-Looking Information.”

4

USE OF PROCEEDS

We intend to use the net proceeds we receive from the sale of our securities, and from the exercise of any warrants issued pursuant hereto, for working capital and other general corporate purposes.

We may set forth additional information regarding the anticipated use of proceeds from the sale of securities we offer under this prospectus in a prospectus supplement relating to the specific offering. We have not determined the amount of net proceeds to be used from any specific offering. As a result, our management will have broad discretion in the allocation of the net proceeds.

5

THE SECURITIES WE MAY OFFER

We may offer and sell, from time to time in one or more offerings, any combination of common stock, preferred stock, warrants, and/or units having an aggregate initial offering price not to exceed $100,000,000. The preferred stock may be convertible into or exchangeable for other shares of our preferred stock, shares of our common stock or warrants. The warrants may be exercisable for shares of our common stock, shares of our preferred stock, and/or units. In this prospectus, we refer to the common stock, preferred stock, warrants and units that we may offer collectively as “securities.”

This prospectus provides a general description of the securities we may offer. Each time we sell any of our securities under this prospectus, we will, to the extent required by law, provide a prospectus supplement that will contain specific information about the terms of the offering. The prospectus supplement may also add, update or change information in this prospectus. For more information, see “About this Prospectus.”

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DESCRIPTION OF CAPITAL STOCK

The following is a summary of all material characteristics of our capital stock as set forth in our amended and restated certificate of incorporation, as amended, or our Charter, and our amended and restated bylaws, or our Bylaws. The summary does not purport to be complete and is qualified in its entirety by reference to our Charter and our Bylaws, copies of which have been filed as exhibits to our SEC filings. For more information, see “Where You Can Find More Information.”

Common Stock

General . We may issue shares of our common stock from time to time. We are currently authorized to issue 135,000,000 shares of common stock, par value $0.001 per share. As of March 31, 2018, there were 83,996,817 shares of our common stock issued and outstanding. Pursuant to a definitive proxy statement filed with the SEC on April 30, 2018, we have asked our stockholders to approve an amendment to our Charter to increase the total number of authorized shares of our common stock by 35,000,000 shares, from 135,000,000 shares to 170,000,000 shares, or the Charter Amendment Proposal. If our stockholders approve the Charter Amendment Proposal at our annual meeting of stockholders to be held on June 14, 2018, we will be authorized to issue 170,000,000 shares of our common stock, par value $0.001 per share. The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any of our outstanding preferred stock.

Dividend Rights . Subject to preferences that may be applicable to any then outstanding shares of preferred stock, holders of common stock are entitled to receive ratably such dividends as may be declared by the board of directors out of funds legally available therefor.

Voting Rights . The holders of our common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the stockholders. The holders of common stock are not entitled to cumulative voting rights with respect to the election of directors, and as a consequence, minority stockholders will not be able to elect directors on the basis of their votes alone.

No Preemptive, Conversion or Similar Rights . Holders of common stock have no preemptive rights and no right to convert their common stock into any other securities.

Right to Receive Liquidation Distributions . In the event of a liquidation, dissolution or winding up, holders of the common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preferences of any then outstanding shares of preferred stock.

Fully Paid and Non-Assessable . All outstanding shares of common stock are, and all shares of common stock to be issued under this prospectus will be, fully paid and non-assessable.

Preferred Stock

Our Charter provides that our board of directors has the authority, without further action by the stockholders, to issue up to 5,000,000 shares of preferred stock in one or more series and to fix the number of shares constituting any series or the designation of a series and to determine or alter for each series or designation of a series the voting powers, if any, and the designations, preferences, and relative, participating, optional, or other rights, and the qualifications, limitations or restrictions, of any series or the designation of a series. Prior to the issuance of shares of each series of preferred stock, the board of directors is required by the General Corporation Law of the State of Delaware, or the DGCL, and our Charter, to adopt resolutions and file a certificate of designation with the Secretary of State of the State of Delaware. The certificate of designation will establish, for each class or series of preferred stock, the rights, preferences, and privileges of such class or series.

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Whenever preferred stock is to be sold pursuant to this prospectus, we will file a prospectus supplement relating to that sale which will specify (in each case to the extent applicable):

The DGCL provides that the holders of preferred stock will have the right to vote separately as a class on any proposed fundamental change in the rights of the preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

All shares of preferred stock offered by this prospectus will, when issued, be fully paid and nonassessable and will not have any preemptive or similar rights.

Delaware Law and Certain Certificate of Incorporation and Bylaw Provisions

The provisions of Delaware law, our Charter and our Bylaws may have the effect of delaying, deferring or discouraging another person from acquiring control of us by means of a tender offer, a proxy contest or otherwise, or removing incumbent officers and directors. These provisions, summarized below, are expected to discourage certain types of coercive takeover practices and takeover bids that our board of directors may consider inadequate and to encourage any person seeking to acquire control of us to first negotiate with our board of directors.

Delaware Law . We are governed by the provisions of Section 203 of the DGCL. In general, Section 203 prohibits a public Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years after the date such stockholder became an “interested stockholder.” A “business combination” includes mergers, asset sales or other transactions resulting in a financial benefit to the stockholder. An “interested stockholder” is a person who, together with affiliates and associates, owns, or within three years did, prior to the determination of interested stockholder status, own, 15% or more of the corporation’s outstanding voting stock. These provisions may have the effect of delaying, deferring or preventing a change in control of our company not approved in advance by our board of directors.

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Charter and Bylaw Provisions . Our Charter and our Bylaws also include a number of other provisions that may have the effect of deterring hostile takeovers or delaying or preventing changes in control or our management as follows:

NASDAQ Global Select Market

Our common stock is listed on the NASDAQ Global Select Market and traded under the symbol “ELGX.” On May 30, 2018, the last reported sale price for our common stock on the NASDAQ Global Select Market was $5.64 per share.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is American Stock Transfer & Trust Company, LLC. The address of American Stock Transfer & Trust Company is 6201 15th Avenue, Brooklyn, NY 11219 and the telephone number is (718) 921-8200.

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DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of shares of common stock, shares of preferred stock and/or units, from time to time. We may issue warrants independently or together with common stock and/or preferred stock, and the warrants may be attached to or separate from those securities. If we issue warrants, they will be evidenced by warrant agreements or warrant certificates issued under one or more warrant agreements, which will be contracts between us and the holders of the warrants or an agent for the holders of the warrants. The forms of warrant agreements or warrant certificates, as applicable, relating to the warrants will be filed as exhibits to the registration statement that includes this prospectus, or as an exhibit to a filing with the SEC that is incorporated by reference into this prospectus.

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DESCRIPTION OF UNITS

We may issue units comprised of one or more of the other securities described in this prospectus in any combination from time to time. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. If we issue units, they will be evidenced by unit agreements or unit certificates issued under one or more unit agreements, which will be contracts between us and the holders of the units or an agent for the holders of the units. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date. The forms of unit agreements or unit certificates, as applicable, relating to the units will be filed as exhibits to the registration statement that includes this prospectus, or as an exhibit to a filing with the SEC that is incorporated by reference into this prospectus.

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PLAN OF DISTRIBUTION

We may sell our securities from time to time in any manner permitted by the Securities Act, including any one or more of the following ways:

The securities may be sold at a fixed price or prices, which may be changed, at market prices prevailing at the time of sale, at prices relating to the prevailing market prices or at negotiated prices.

Offers to purchase offered securities may be solicited by agents designated by us from time to time. Any agent involved in the offer or sale of the offered securities in respect of which this prospectus is delivered will be named, and any commissions payable by us will be set forth, in the applicable prospectus supplement. Unless otherwise set forth in the applicable prospectus supplement, any agent will be acting on a reasonable best efforts basis for the period of its appointment. Any agent may be deemed to be an underwriter, as that term is defined in the Securities Act, of the offered securities so offered and sold.

We will set forth in a prospectus supplement the terms of the offering of our securities, including:

If offered securities are sold to the public by means of an underwritten offering, either through underwriting syndicates represented by managing underwriters or directly by the managing underwriters, we will execute an underwriting agreement with an underwriter or underwriters, and the names of the specific managing underwriter or underwriters, as well as any other underwriters, will be set forth in the applicable prospectus supplement. In addition, the terms of the transaction, including commissions, discounts and any other compensation of the underwriters and dealers, if any, will be set forth in the applicable prospectus supplement, which prospectus supplement will be used by the underwriters to make resales of the offered securities. If underwriters are utilized in the sale of the offered securities, the offered securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions, including:

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We may grant to the underwriters options to purchase additional offered securities to cover over-allotments, if any, at the public offering price with additional underwriting discounts or commissions, as may be set forth in the applicable prospectus supplement. If we grant any over-allotment option, the terms of the over-allotment option will be set forth in the applicable prospectus supplement.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may indemnify agents, underwriters and dealers against specified liabilities, including liabilities incurred under the Securities Act, or to contribution by us to payments they may be required to make in respect of such liabilities. Agents, underwriters or dealers, or their respective affiliates, may be customers of, engage in transactions with or perform services for us or our respective affiliates, in the ordinary course of business.

Unless otherwise specified in the applicable prospectus supplement, each class or series of securities will be a new issue with no established trading market, other than our common stock, which is traded on the NASDAQ Global Select Market. We may elect to list any other class or series of securities on any exchange and, in the case of our common stock, on any additional exchange. However, unless otherwise specified in the applicable prospectus supplement, we will not be obligated to do so. It is possible that one or more underwriters may make a market in a class or series of securities, but the underwriters will not be obligated to do so and may discontinue any market making at any time without notice. We cannot give any assurance as to the liquidity of the trading market for any of the offered securities.

Any underwriter may engage in over-allotment, stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Securities Exchange Act of 1934, as amended, or the Exchange Act. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum price. Syndicate-covering or other short-covering transactions involve purchases of the securities, either through exercise of the over-allotment option or in the open market after the distribution is completed, to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.

To comply with the securities laws of certain states, if applicable, the securities offered by this prospectus will be offered and sold in those states only through registered or licensed brokers or dealers.

In compliance with guidelines of the Financial Industry Regulatory Authority, or FINRA, the maximum consideration or discount to be received by any FINRA member or independent broker dealer may not exceed 8% of the aggregate amount of the securities offered pursuant to this prospectus and any applicable prospectus supplement.

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LEGAL MATTERS

Certain legal matters, including the validity of the issuance of the securities offered by this prospectus, will be passed upon for us by Stradling Yocca Carlson & Rauth, P.C., Newport Beach, California.

EXPERTS

The consolidated financial statements and schedule of Endologix, Inc. as of December 31, 2017 and 2016 and for each of the years in the three-year period ended December 31, 2017, and management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2017, have been incorporated by reference herein in reliance upon the reports of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

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INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate” into this prospectus information that we file with the SEC in other documents. This means that we can disclose important information to you by referring to other documents that contain that information. Any information that we incorporate by reference into this prospectus is considered part of this prospectus.

Information contained in this prospectus and information that we file with the SEC in the future and incorporate by reference in this prospectus automatically modifies and supersedes previously filed information, including information in previously filed documents or reports that have been incorporated by reference in this prospectus, to the extent the new information differs from or is inconsistent with the old information. Any statement so modified will be deemed to constitute a part of this prospectus only as so modified, and any statement so superseded will be deemed not to constitute a part of this prospectus. For more information, see “About this Prospectus.”

We incorporate by reference, as of their respective dates of filing, the documents listed below that we have filed with the SEC and any future documents that we file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including any documents filed after the date of the initial registration statement of which this prospectus is a part until the offering of the securities covered by this prospectus has been completed, other than, in each case, documents or information deemed to have been “furnished” and not “filed” in accordance with SEC rules:

These filings have not been included in or delivered with this prospectus. We will provide to each person, including any beneficial owner to whom this prospectus is delivered, a copy of any document that is incorporated by reference in this prospectus. You may obtain a copy of these documents, at no cost, from our website (www.endologix.com) or by contacting us using the following information:

Endologix, Inc.

2 Musick

Irvine, California 92618

Attention: Investor Relations

(949) 595-7200

Exhibits to the documents will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus.

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You should rely only on the information contained in this prospectus, in any accompanying prospectus supplement, or in any document incorporated by reference herein or therein. We have not authorized anyone to provide you with any different information. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may provide to you. The information contained in this prospectus, in any applicable prospectus supplement, and in the documents incorporated by reference herein or therein is accurate only as of the date such information is presented. Our business, financial condition, results of operations and future prospects may have changed since those respective dates.

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WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports and other information with the SEC. You may read and copy any document we file at the SEC’s Public Reference Room located at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the public reference room by calling the SEC at 1-800-SEC-0330. Our filings with the SEC also are available from the SEC’s website at www.sec.gov, which contains reports, proxy and information statements, and other information regarding issuers that file electronically.

This prospectus is part of a registration statement that we filed with the SEC. As permitted by SEC rules, this prospectus and any accompanying prospectus supplement that we may file, which form a part of the registration statement, do not contain all of the information that is included in the registration statement. The registration statement contains more information regarding us and our securities, including certain exhibits. You can obtain a copy of the registration statement from the SEC at the address listed above or from the SEC’s website.

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$25,000,000

Common Stock

PROSPECTUS SUPPLEMENT

Piper Jaffray

August 13, 2019